How a transformer works
A transformer has two coils of wire on one iron core, and the coils are not wired to each other. AC in the first coil makes a changing field, and that field makes a voltage in the second coil. You change the turns ratio and the lamps and watch the voltage and current.
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What to try
- 1Start on 5 to 1 with one lamp. The primary gets 120 volts, and the secondary makes 24 volts.
- 2Set Lamps to Two. Both coils carry twice the current, and the power out still matches the power in.
- 3Pick Battery (DC). The field builds up once, so the secondary gets one short pulse and then nothing. Never put DC on a transformer.
NEC 2026 sections it covers
- 120.5(A)
- 120 V is a nominal system voltage.
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More visuals
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- Volts, amps, and ohmsChange the voltage or the heater and watch the amps follow. Amps equal volts divided by ohms.